This invention relates to electrical machinery and, more particularly, to an improved rotor assembly for electric machines.
An electrical generating system may be coupled to similar systems in parallel to form a multi-channel generating system. The multi-channel system provides continuous current flow to a load. Each channel has an alternator and each alternator has a rotor and a stator. A stator voltage acting upon the rotor establishes a flux coupling between the rotor and the stator. Because of the flux coupling, motoring of a rotor can occur when its prime mover has been disconnected from the system and its field windings have been deenergized. To overcome this problem over-running clutches have been used to mechanically disconnect the rotor from the prime mover when the generating system is to be removed from the other generating systems. However, the use of over-running clutches has not always been desirable since they are often of questionable reliability. Also, shorted damper bars have been inserted at the ends of the poles of the rotor to improve the response of the rotor to voltages impressed by the stator. This particular structure is typical of synchronous generators and has a large mutual flux coupling between the rotor and the stator. It is not desirable for use in multi-channel generating systems because it acts as an induction motor when energized by other generating systems.
Accordingly, I have developed an improved rotor assembly for an electrical generating system which is not greatly affected by voltages impressed upon it by the stator and has a reduced mutual coupling between the stator and the rotor.